<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <meta name="keywords" content="keyword1,keywords2,keywords3"/>
    <meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
</head>
<body>
<form method="post" enctype="multipart/form-data" th:action="@{/addMainTest}">
  文件：<input type="file" placeholder="请选择文件" name="fileName"><br/>

        <input type="submit" value="提交">
</form>
</body>
</html>